Composite or Sideloading? - api

Question

I am relatively new to building APIs and have come across the following two terms a few times now and am a bit confused. I'm hoping someone can put me straight with some definitions that I cannot even find on wikipedia. Im not sure if they can be reliably used interchangeably without upsetting people or whether it depends on who you talk to.
Sideloading
the ability to optionally include other related resource(s) in a response
eg. /accounts?include=transactions will include transactions resources in my /accounts resources response ?
this really means that we avoid duplication of resources in a response by moving them out into their own section of the message, eg.instead of
{ "orders": [ {
"id": "101",
"product": { "id": "2000", "desc": "blah", "price": "100.0" }
"id": "102",
"product": { "id": "2000", "desc": "blah", "price": "100.0" }
we would have:
{ "orders": [ {
"id": "101",
"product": { "id": "2000" }
"id": "102",
"product": { "id": "2000" }
],
"products": [
{ "id": "2000", "desc": "blah", "price": "100.0" }
Composite Document
Simply means you have a mix of related resources (that can also stand alone) in a resources response eg. accounts and transactions resources can be requested on their own or also combined in the same composite document ??

Answer 1

I've never come across what I would consider a formal definition of either sideloading or composite, I reckon you can define it how you want, provided its consistent with how your resources are modelled.
I cant imagine people getting too upset about the terminology. The basic premise is sound, everything else is just semantics and implementation :). That said, it's a good idea to keep your API object model relatively pure and functional for the client.
So if it is most likely to be used in the nested product fashion, and thats what the API naturally looks like, then the duplication of
{ "orders": [ {
"id": "101",
"product": { "id": "2000", "desc": "blah", "price": "100.0" }
"id": "102",
"product": { "id": "2000", "desc": "blah", "price": "100.0" }
might be less of a problem than the added indirection of
{ "orders": [ {
"id": "101",
"product": { "id": "2000" }
"id": "102",
"product": { "id": "2000" }
],
"products": [
{ "id": "2000", "desc": "blah", "price": "100.0" }